No Rings Around Rhea

They would have been the first rings ever observed around a moon: three narrow bands of icy debris encircling Saturn's second-largest satellite, Rhea. Space physicists announced their existence in March 2008. But a more definitive search finds that they simply aren't there. And that raises the question of what exactly the first team saw.

The original ring detection was based on plasma measurements the Cassini spacecraft made while orbiting Saturn in 2005. In a 2008 paper in Science, space physicist Geraint Jones of University College London and colleagues described how some unseen solid material around Rhea, which is less than half the size of our moon, seemed to be absorbing energetic electrons that are trapped in Saturn's magnetosphere. …